Mercury cadmium telluride Hg.sub.1-x Cd.sub.x Te can be grown on CdTe substrates by liquid phase epitaxy from a Te-rich solution at atmospheric pressure, in which case the Hg pressure will be below 0.1 atm for growth temperatures below 500.degree. C. This low pressure makes possible the use of open-tube, slider growth techniques.
Mercury cadmium telluride can be grown by liquid phase epitaxy from solutions of metal (Hg, Cd), of HgTe (along the pseudobinary) or of Te. The schematic He-Cd-Te ternary phase diagram for Hg.sub.1-x Cd.sub.x Te is shown in FIG. 1 and three solutions are shown which are in equilibrium with Hg.sub.0.6 Cd.sub.0.4 Te. Thus such a given composition can be grown from a Te-rich solution (line a), from a Hg-rich solution (line b) or from a HgTe rich solution (along the pseudobinary line c). One practical difference among these approaches is the Hg vapor pressure present in each case. With the Te-rich solution, the Hg vapor pressure is only 0.1 atm at 500.degree. C. The Hg vapor pressure over a Hg rich solution is much higher, that is, 7 atm at 500.degree. C.
Even with a low Hg vapor pressure of 0.1 atm there is a problem that excessive Hg will be lost. Since H.sub.2 gas flows through the furnace tube during the entire equilibration and growth process, much Hg vapor is required to saturate the H.sub.2 gas during a run. The present invention describes a covered graphite slider system which provides a source of Hg, minimizes loss of Hg from the source wafer and virtually prevents loss of Hg from the growth solution.